Apple's teasing commercials that imply its software is safer than Microsoft's may not quite match the facts, according to new research revealed at the Black Hat conference on Thursday.

Researchers from the Swiss Federal Institute of Technology looked at how many times over the past six years the two vendors were able to have a patch available on the day a vulnerability became publicly known, which they call the 0-day patch rate .

They analyzed 658 vulnerabilities affecting Microsoft products and 738 affecting Apple. They looked at only high- and medium-risk bugs, according to the classification used by the National Vulnerability Database, said Stefan Frei, one of the researchers involved in the study. What they found is that, contrary to popular belief that Apple makes more secure products, Apple actually lags behind in patching.